Some embodiments relate to a valve equipping the non-return pump of an airless dispensing system, i.e., one without air intake, such that the product dispensed is never in contact with the air before it is dispensed. This type of airless dispensing system is used to dispense products which are liable to deteriorate in contact with the air. They may be, for example, pharmaceutical products, cosmetic products such as care creams with a fluid, i.e., liquid or pasty, consistency. Since there is a desire to eliminate preservatives in creams, it is necessary to protect them from the air. The fluid product is thus packaged in a retractable container such that the volume of the container corresponds precisely to the remaining quantity of product it contains at any time of use, the product never being in contact with the air inside the container.
A related art dispenser includes a pump equipped with an inlet valve and an outlet valve. It is connected to the container in a leaktight manner and has, at the outlet of the pump, an evacuation duct that opens out at an orifice, the pump being actuated by a push button. The leaktightness of the valves equipping the pump is essential to allow proper operation of the pump and to ensure the airtightness of the dispensing system. In order to meet this objective, the valves of the pumps are usually formed by complex elements incorporating balls or flaps, both of which are able to move, guides, presser of the spring type for pressing, opening and closing stops, etc. These complex systems ensure the leaktightness of the valve when it is in the closed position and more particularly when the dispensing system is at rest. The dispensing system is at rest when the pressures inside the container and inside the pump and atmospheric pressure are identical. The inlet and outlet valves of the pump are then closed and airtight.
Furthermore, creams are increasingly water-based emulsions and the containers in which the cream is packaged are by definition closed in a leaktight manner. The water of these emulsions tends to turn into water vapour when it is enclosed in a closed container and when the temperature is greater than 0° C. The change of the water from the liquid phase to the gaseous phase creates an overpressure in the container. It is essential, when the pump is at rest, that the valves be leaktight in spite of the overpressure inside of the container with respect to atmospheric pressure.
The related art pumps which equip the airless dispensing systems are thus generally complex, sometimes fragile, and made up of a large number of parts, this complicating manufacturing and increasing the cost, especially since these components are generally miniaturized.